Bitcoins, like online gaming characters and savings accounts, are in danger of being lost when we die. Photograph: Rick Bowmer/AP

Don't forget where you squirrelled away the Bitcoins; keep track of online gaming characters; save your passwords for photographs and savings accounts or risk it all disappearing down the back of the internet. In other words, leave a digital legacy, the Law Society is urging.

Updating advice for writing wills in the 21st century, the organisation which represents solicitors across England and Wales has warned that too much valuable, intellectual property is in danger of being lost when we die.

Never record your passwords, however, in a written will: you are likely to have changed them by the time you finally log off. Furthermore, wills are public documents that can be published.

Some assets, the Law Society cautions, will not survive beyond your lifetime. In many cases, we are merely sold licences to use online music, films and books preventing them from being passed on to others. That applies to Kindle ebooks, the Law Society says.

At one point it was widely reported that film star Bruce Willis was planning to join a legal action against Apple so that he could leave his iTunes music library to his daughters. Having spread across the web, the story's credibility was subsequently questioned.

As well as Bitcoins, the value of which oscillates according to volatile online trading conditions, digital gaming characters can also be worth significant sums after they have accumulated successful track records and digital equipment.

"People should leave clear instructions about what should happen to their social media, computer games and other online accounts after their death," the Law Society recommends. "Having a list of all your online accounts, such as email, banking, investments and social networking sites will make it easier for family members to piece together your digital legacy, adhere to your wishes and could save time and money. Not making your digital legacy clear could mean important or sentimental material – such as photographs on social networks – is never recovered."

Gary Rycroft, a solicitor with Joseph A Jones & Co in Lancaster who is on the Law Society's wills and equity committee, said people should not assume that family members know where to look online.

"If you have a Twitter account, your family may want it deactivated and – if you have left clear instructions – it will be easier for your executors to have it closed," he said. "If you have an online bank account, your executors will be able to close it down and claim the money on behalf of your estate."

The Law Society's president, Nicholas Fluck, said: "As technology has evolved, so has the way we store information. Simple things such as photographs, which in the past we could have flicked through in a printed album, are now stored online. By making our wishes clear now, it will be easier for loved ones to recover pictures to cherish and will help with the more practical issues such as online bank accounts."